The therapy, designed to treat Parkinson’s disease, delivers 3 genes into the area of the brain responsible for controlling movement, the striatum, using a modified virus which is closely related to HIV. The idea is that the genes will boost the body’s production of the chemical dopamine, in which Parkinson’s sufferers are deficient. The therapy hopes to offer a long-term solution which will stimulate ongoing dopamine production in a different group of cells.

The treatment was first tested on rats and then primates, with surprising results, enabling movement in monkeys that had been disabled before treatment commenced. 15 trial participants were selected for the tests – 12 from France and 3 from the UK – all with advanced Parkinson’s disease. The results show that participant’s scores on movement assessment tests increased by an average of 30%, with results sustained over a 4 year follow up. Scans over this period revealed that participant’s brains were continuing to produce dopamine.

More extensive trials will take place once the delivery method and dose has been optimised by researchers.